static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
prepare_to_copy(orig);
tsk = alloc_task_struct();
if (!tsk)
return NULL;
ti = alloc_thread_info(tsk);
if (!ti) {
free_task_struct(tsk);
return NULL;
}
*tsk = *orig;
tsk->thread_info = ti;
setup_thread_stack(tsk, orig);
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
atomic_set(&tsk->fs_excl, 0);
tsk->btrace_seq = 0;
tsk->splice_pipe = NULL;
return tsk;
}
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
prepare_to_copy(orig);
tsk = alloc_task_struct();
if (!tsk)
return NULL;
ti = alloc_thread_info(tsk);
if (!ti) {
free_task_struct(tsk);
return NULL;
}
*ti = *orig->thread_info;
*tsk = *orig;
tsk->thread_info = ti;
ti->task = tsk;
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
return tsk;
}
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
prepare_to_copy(orig);
tsk = alloc_task_struct();
if (!tsk)
return NULL;
ti = alloc_thread_info(tsk);
if (!ti) {
free_task_struct(tsk);
return NULL;
}
*tsk = *orig;
tsk->stack = ti;
setup_thread_stack(tsk, orig);
#ifdef CONFIG_CC_STACKPROTECTOR
tsk->stack_canary = get_random_int();
#endif
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
atomic_set(&tsk->fs_excl, 0);
#ifdef CONFIG_BLK_DEV_IO_TRACE
tsk->btrace_seq = 0;
#endif
tsk->splice_pipe = NULL;
return tsk;
}
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
unsigned long *stackend;
int err;
prepare_to_copy(orig);
tsk = alloc_task_struct();
if (!tsk)
return NULL;
ti = alloc_thread_info(tsk);
if (!ti) {
free_task_struct(tsk);
return NULL;
}
err = arch_dup_task_struct(tsk, orig);
if (err)
goto out;
tsk->stack = ti;
err = prop_local_init_single(&tsk->dirties);
if (err)
goto out;
setup_thread_stack(tsk, orig);
clear_user_return_notifier(tsk);
clear_tsk_need_resched(tsk);
stackend = end_of_stack(tsk);
*stackend = STACK_END_MAGIC; /* for overflow detection */
#ifdef CONFIG_CC_STACKPROTECTOR
tsk->stack_canary = get_random_int();
#endif
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
atomic_set(&tsk->fs_excl, 0);
#ifdef CONFIG_BLK_DEV_IO_TRACE
tsk->btrace_seq = 0;
#endif
tsk->splice_pipe = NULL;
account_kernel_stack(ti, 1);
return tsk;
out:
free_thread_info(ti);
free_task_struct(tsk);
return NULL;
}
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
prepare_to_copy(orig);
/*
* 为新进程获取进程描述符
*/
tsk = alloc_task_struct();
if (!tsk)
return NULL;
/*
* 获取一片空闲区域4k或者8k, 用来存放新进程的thread_info结构和内核栈
*/
ti = alloc_thread_info(tsk);
if (!ti) {
free_task_struct(tsk);
return NULL;
}
/*
* 将current进程描述符的内容复制到tsk所指向的task_struct结构中
*/
*ti = *orig->thread_info;
/*
* 把current进程的thread_info描述符的内容复制到ti中
*/
*tsk = *orig;
/*
* 下面两行将新进程的task_struct与thread_info绑定
*/
tsk->thread_info = ti;
ti->task = tsk;
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
return tsk;
}
int import_thread_info(struct epm_action *action,
ghost_t *ghost, struct task_struct *task)
{
struct thread_info *p;
int r;
p = alloc_thread_info(task);
if (!p) {
r = -ENOMEM;
goto exit;
}
r = ghost_read(ghost, p, sizeof(struct thread_info));
/* Required by [__]free_thread_info() */
p->task = task;
if (r)
goto exit_free_thread_info;
p->exec_domain = import_exec_domain(action, ghost);
p->preempt_count = 0;
p->addr_limit = USER_DS;
r = import_restart_block(action, ghost, &p->restart_block);
if (r)
goto exit_free_thread_info;
task->stack = p;
exit:
return r;
exit_free_thread_info:
__free_thread_info(p);
goto exit;
}
/*
* 由do_fork()调用，为新的子进程创建task_struct, thread_info, 内核栈等信息
* 创建完成之后和父进程状态完全相同
*/
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
struct task_struct *tsk;
struct thread_info *ti;
unsigned long *stackend;
int err;
prepare_to_copy(orig);
/* 申请task_struct内存空间 */
tsk = alloc_task_struct();
if (!tsk)
return NULL;
/* 申请thread_info内存空间 */
ti = alloc_thread_info(tsk);
if (!ti) {
/* 失败需要释放前面已经成功申请的task_struct内存空间，防止内存泄漏 */
free_task_struct(tsk);
return NULL;
}
/* 复制orig进程的信息到tsk进程中，复制完成后地址空间地址相同 */
err = arch_dup_task_struct(tsk, orig);
if (err)
goto out;
tsk->stack = ti;
/* 清空新进程的部分标志 */
err = prop_local_init_single(&tsk->dirties);
if (err)
goto out;
/* 新进程的进程栈信息 */
setup_thread_stack(tsk, orig);
/* 清除进程栈的部分信息 */
clear_user_return_notifier(tsk);
clear_tsk_need_resched(tsk);
stackend = end_of_stack(tsk);
*stackend = STACK_END_MAGIC; /* 用作内存越界检测 */
#ifdef CONFIG_CC_STACKPROTECTOR
tsk->stack_canary = get_random_int();
#endif
/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
atomic_set(&tsk->fs_excl, 0);
#ifdef CONFIG_BLK_DEV_IO_TRACE
tsk->btrace_seq = 0;
#endif
tsk->splice_pipe = NULL;
/* 内核栈??? 干啥的??? */
account_kernel_stack(ti, 1);
return tsk;
out:
free_thread_info(ti);
free_task_struct(tsk);
return NULL;
}